With the increasing scarcity of fuel and its rising cost, a number of devices have been proposed to warn an automobile driver when he is accelerating too rapidly for acceptable fuel economy. An example of such a device is a warning sound or light actuated by intake manifold pressure which increases as the rate of acceleration increases. A disadvantage of such a device is that the driver's attention may not be attracted by the warning signal and even if it is, the driver will not know how much to reduce his acceleration in order to avoid excessive fuel consumption. He will thus have to hunt with the pedal in an attempt to synchronize the throttle opening with acceptable economy.
An important object of the present invention is to provide a device for causing a detectable increase in the force required by the driver to depress the customary throttle control pedal when acceleration becomes excessive, which increase in force will be eliminated as soon as the throttle pedal is released sufficiently to effect a predetermined rate of acceleration for acceptable fuel economy.
Other objects are to provide such a device which the driver may readily overpower at his option when rapid acceleration becomes desirable, and which may be selectively rendered inoperative, as for example during expressway driving, so that the driver may accelerate at any rate within the capability of the automobile without experiencing more than customary throttle pedal reaction force.
Another object is to provide such a device responsive to an operating condition of the automobile, as for example the intake manifold pressure, which yieldably opposes throttle opening movement by means of a supplementary spring force when the automobile engine is accelerated at more than a predetermined rate, and which enables return movement of the throttle to its closed position independently of the opposing device in the event the latter should become jammed or stuck.
Other objects are to provide such a device which may be readily calibrated to serve either as a speed limit sensor or as a rate of acceleration sensor and which comprises a spring urged member in the path of opening movement of the throttle to oppose such movement, in combination with pressure actuated means responsive to an operating condition of the automobile, such as inlet manifold pressure, for withdrawing the spring urged member from said path during idle or steady state operation and low rate acceleration suitable for city driving for example with acceptable fuel economy.